1. Field of the Invention
This invention pertains to catheters for collecting fluid from a blood vessel of a patient.
2. Description of the Prior Art
Collection catheters are well known for collecting blood or other fluids from blood vessels of a patient. For example, International Publication No. WO 2005/082440 A1 describes collection catheters for collecting blood from a coronary sinus or other coronary vein in a perfusion system.
In addition to collecting blood in a perfusion process, blood may be collected from a coronary vein in an angiography procedure. Such procedures are used for assessing patency of coronary arteries. These procedures may also be used for other purposes—for example, in stent placement or other procedures. In such a procedure, a contrast medium is injected into a coronary artery proximal to a suspected site of a coronary obstruction.
Contrast media may have significant health risks if permitted to flow systemically to the patient's organs. For example, renal dysfunction or failure may occur from such systemic delivery of a contrast media. Such failure is referred to as “contrast-induced nephropathy” or CIN. Schräder, “Contrast Media-Induced Renal Failure: And Overview”, Journal of Interventional Cardiology, Vol. 18, No. 6, pages 417-423(2005).
A number of different techniques in catheter designs have been suggested for collecting contrast media. Examples of such are shown in U.S. Pat. No. 6,554,819 to Reich issued Apr. 29, 2003; U.S. Patent Application Publication No. US 2002/0099254 A1 to Movahed published Jul. 25, 2002; U.S. Patent Application Publication No. US 2005/0256441 A1 to Lotan et al., published Nov. 17, 2005, U.S. Patent Application Publication No. 2005/0124969 to Fitzgerald et al. published Jun. 9, 2005 and U.S. Patent Application Publication No. US 2006/0013772 A1 to LeWinter et al., published Jan. 19, 2006. A contrast removal system is also described in Michishita, et al. “A Novel Contrast Removal System From The Coronary Sinus Using An Absorbing Column During Coronary Angiography In A Porcine Model”, Journal of the American College of Cardiology, Vol. 47, No. 9 (2006).
Blood collected in a contrast removal or other blood collection system may be processed to be re-admitted to the patient. However, it is more common for collected blood to be discarded. It is generally recognized that a limited amount (e.g., 100 milliliters to 200 milliliters) of blood may be safely removed from a patient and discarded.
Blood collection techniques include methods and apparatus for isolating blood flow in a vessel. This insures that substantially all antegrade flow (i.e., the normal direction of blood flow in a vessel) is collected for a period of time to substantial collect all contrast media or perfusate which is the object of collection.
Importantly, such isolation is employed to avoid collection of retrograde blood flow. Retrograde flow (in a direction opposite normal blood flow in a vessel) may occur, for example, where a catheter draws blood from a coronary sinus under suction. The suction may be such that blood in the right atrium flows retrograde and is drawn through the catheter. As a result, blood not laden with contrast media or perfusate is collected and possibly discarded. Since there are limits on how much blood may be discarded, it is desirable to avoid collecting and discarding blood not laden with contrast media or perfusate.
Isolation is commonly achieved through use of balloon catheters. A balloon is inflated during periods of blood collection to seal against the wall of the blood vessel. Otherwise, the balloon is deflated to be spaced from the blood vessel wall.
During an angiography, contrast media may be injected at multiple times during a procedure. To collect such contrast media, a balloon is repeated inflated and deflated in a manner timed with the injection. However, it is difficult to precisely coordinate the timing of the inflation and deflation with the withdrawal of blood from the catheter. Maintaining occlusion constantly is undesirable since this may lead to venous congestion and shunting of contrast-laden blood from a coronary sinus to the right atrium through collateral veins.
It is an object of the present invention to provide a method and apparatus for collection of a fluid from a blood vessel.